Use of Construction and Demolition Waste for the Treatment of Dye-Contaminated Water Toward Circular economy

The use of construction and demolition waste (CDW) for the treatment of dye-contaminated water can be an effective way to minimize environmental impacts. This study evaluates its adoption as a potential adsorbent for methylene blue (MB) in aqueous solution. Cement mortar, roof tiles, and tiles were disintegrated and sieved for physicochemical characterization (pH, potential redox - Eh, electrical conductivity - CE, cationic exchange capacity-CEC, point of zero charge - PZC, specific surface area - SSA, pore distribution, functional groups, and elemental composition). The effect of initial concentration, pH, granulometric fraction and time were evaluated in adsorption and desorption studies. The results of adsorption studies were analyzed using nonlinear kinetic models and equilibrium data were analyzed by Langmuir, Freundlich, Sips, and Temkin isotherm models. The CDW evaluated has alkaline pH (pH 8.4 - 11.6) with high EC (680.5 - 1054.5 mu S cm(-1)), reductive environment (-223 - -66 mV), low CEC (0.45 - 1.40 cmol(c) kg(-1)), SSA (1.83 - 11.06 m(2) g(-1)), and basic PZC (8.3 - 10.0). Initial concentration, pH and adsorbent particle size affected the removal efficiency and desorption rate. Roof tiles showed higher MB removal efficiency (84.5%), followed by cement mortar (61.1%) and tiles (41.6%), and the materials displayed the following maximum adsorption capacities (q(m)): tiles (13.983 mg g(-1)) > roof tiles (8.389 mg g(-1)) > cement mortar (1.305 mg g(-1)). Pseudo-first order model best described the chemical kinetics. Freundlich isotherm best described the adsorption process of MB onto tiles and Sips model best described the process onto roof tiles and cement mortar. Therefore, the materials can be used for removing MB from aqueous solutions.